"Dave Fawthrop" wrote in message
...
On 27 Feb 2007 01:41:41 GMT, Ian Stirling wrote:

|!Weatherlawyer wrote:
|! On Feb 26, 12:03 pm, John Rumm wrote:
|! Lurch wrote:
|!
http://www.screwfix.com/search.do;js...ABOCSTHZOCFEY?...
|! If you load the instruction manual for the rotary the accuracy
which
|! is quoted in +/- mm per m is 1 which seems an awful lot. At 5m you
are
|! going to be 5 mm out (possibly)
|!
|! Most fixed levels are accurate to around 1mm in 1000mm so not
really
|! any different.
|!
|! A slight difference being that if you were transferring a level a
long
|! distance with a conventional level, then you would (well should!)
|! reverse it each time you extend the level - that way you reverse out
any
|! error each time. With a laser level you would not do this, so the
base
|! accuracy needs to be better really.
|!
|! The spec. in the booklet is 0.15 degrees per metre. That isn't a great
|! deal of inaccuracy.With the rotary one the range is 30 metres so the
|! inaccuracy -if it remains at 0.15 degrees per metre over the full
|! range, is 4.5 degrees.
|!
|!Except in the very largest of rooms, the beam does not curve.

All beams curve *a little* even when the load is only the weight of the
beam itself. This may be very little, indeed not measurable with DIY
tools.

woooosh